Engineering Science and Materials Commons^™

Effect Of Gating Design On Filling And Inclusion Control In An Al-Killed Cr-Mo-Ni Steel, Kingsley T. Amatanweze, Koushik Balasubramanian, Soumava Chakraborty, Viraj A. Athavale, Mario F. Buchely, Laura N. Bartlett, Ronald J. O'Malley, Daniel M. Field, Krista R. Limmer, Katherine M. Sebeck

Materials Science and Engineering Faculty Research & Creative Works

The effect of gating system design on the inclusion population and size distribution in an aluminum-killed low-alloy advanced high strength steel casting was studied. A mold with four different gating systems: pressurized and non-pressurized with side risers, naturally pressurized with a side riser, and naturally pressurized with a top riser, was designed using computational fluid dynamics and solidification software. The design allowed inclusion populations in castings produced with each gating system to be compared during the same pouring event. Samples taken from different positions just below the top surface of each casting were analyzed using an SEM/EDS system with automated …

Reuse Of Calcium Carbonate (Caco3) Recovered From Discarded Carpets As Filler In Fiber-Reinforced Polymer (Frp) Composites, Roshan Devkota

Graduate Theses, Dissertations, and Problem Reports (ETD)

Over four billion pounds of carpet are discarded annually in the United States, making carpet waste a significant environmental concern. Calcium carbonate (CaCo₃) constitutes up to 45% of the mass of most synthetic carpets. Reusing this CaCo₃ as a filler in the rapidly growing fiber-reinforced polymer (FRP) industry, which is projected to reach USD 10.38 billion, presents a low-cost, practical approach to developing a market-based solution to post-consumer carpet waste.

This study investigates the reuse of CaCo₃ recovered from discarded carpet backing as a filler in FRP composites, focusing on its mechanical viability in comparison to virgin CaCo₃. The methodology …

Metakaolin-Based Geopolymer Concrete; Synthesis, Development And Characterization, Heba Fouad

Theses and Dissertations

Geopolymers are rendered as an essential sustainable replacement to the widely used Ordinary Portland Cement (OPC) which causes immense carbon dioxide emissions, hence a detrimental impact on society’s health and the environment. Geopolymers are three-dimensional networks of polymerized tetrahedral silicate and aluminate in the form of Q4(4Al), Q4(3Al) and Q4(2Al) which act as the principal binding phase in concrete. Past research has reported the synthesis of geopolymers from different aluminosilicates precursors, their characterization, and their wide range properties. However, previous studies still have not properly investigated effective range of synthesis ratios for a particular source material, optimum curing regimes, short- …

Thermal Conductivity Characterization Of High Oleic Vegetable Oils Based Hybrid Nanofluids Formulated Using Gnp, Tio2, Mos2, Al2o3 Nanoparticles For Mql Machining, Anthony Chukwujekwu Okafor, Tobechukwu Kingsley Abor, Saidanvar Esanjonovich Valiev, Ignatius Echezona Ekengwu, Abiodun Saka, Monday Uchenna Okoronkwo

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents the results of thermal conductivity characterization of six high oleic soybean oil (HOSO) and four high oleic canola oil (HOCO)-based hybrid nanofluids formulated with four types of nanoparticles (Graphene nanoplatelet (xGnP), TiO2, MoS2, and Al2O3) at nanoparticles wt.% concentration from 1 % to 7 % in 1 % increment using the two-step method for use in MQL machining of difficult-to-cut metals. Thermal conductivity of the formulated hybrid nanofluids were measured using Thermtest Transient Hot Wire Liquid Thermal Conductivity Meter at temperatures from 25 °C to 75 °C in increment of 10 °C. Obtained results showed that thermal …

Development Of Machine Learning-Based Tool For Prediction Of Long-Term Field Performance Of Asphalt Concrete Overlays In A Hot And Humid Climate, Elise Mansour

LSU Doctoral Dissertations

The performance of pavement plays a critical role in Maintenance, Rehabilitation and Reconstruction (MR&R) for highway agencies. Reliable and accurate estimation of pavement performance can be instrumental in prioritization of the limited resources and funding for highway agencies. The latter requires robust prediction models that can handle large-scale, real-world data and can forecast pavement performance in the long run. Unfortunately, the traditional performance prediction models have raised concerns regarding their efficiency and accuracy. It is because these models were based on a limited number of explanatory variables, were not up-to-date and were designed for forecasting short-term (up to five years) …

Analyzing The Key Characteristics And Benefits Of Ccpr (Cold Central Plant Recycling) In Road Rehabilitation And Sustainability, Bassam Abou Yassine

Civil Engineering ETDs

Cold mix asphalt (CMA) technologies are being used in the United States and have environmental benefits. However, these technologies are not fully developed. We do not yet know their resilient and dynamic modulus, which are important for designing pavement thickness. They have not being used widely because we do not know also their performance. This study looks at three Cold Central Plant Recycling (CCPR) materials to help fill this gap. We conducted several lab tests, including the Hamburg Wheel Tracking Test (HWTT), Semi-Circular Bending Test (SCB), and Texas Overlay Test (TOT). We also tested the mechanical properties of the CCPR …

Effect Of Addition Monofilament And Multifilament Polypropylene Fibers On Mechanical Properties Of Concrete At Elevated Temperatures, Nourhan Osama Hanafy Dr

Journal of Engineering Research

Some researchers studied the effect of different types of fibers on the strengths of concrete at elevated temperature. However, there are some limitations in the study of the strengths of concrete using different methods of cooling after elevated temperature. Thus, the main objective of this research is to study the mechanical properties of concrete with the addition of 1% polypropylene fibers, featuring different structures, at elevated temperatures and with various cooling methods, compared to normal concrete. An experimental program using three different series of mixes, the first series included normal concrete (control) mix without fibers, the second series included 1% …

Effects Of Titanium Particulates On Concrete Compressive Strength, Ryan Christopher Brunello

Construction Management

Titanium has the potential to increase the compressive strength of concrete. This experiment investigates the impact of titanium admixture on concrete compressive strength, using three different forms of titanium: shavings, flakes, and powder. This experiment goes further, evaluating the effects of varying proportions of titanium admixture, ranging from 1% - 5% by the weight of cement, resulting in 15 different concrete test cylinders and one additional cylinder as the control variable with no titanium admixture. This experiment aims to identify the optimal recipe for concrete mix with titanium admixture which can provide valuable insight to the industry as to how …

Microwave Catalysis-Enabled Membrane Processes For Microbial Inactivation, Fangzhou Liu

Dissertations

The COVID-19 pandemic has highlighted the urgent need for advanced technologies to combat virus transmission. Traditional membrane filtration technologies primarily serve as physical barriers, capturing pollutants but failing to inactivate microbial agents such as bacteria and viruses. These membranes typically target larger particles but are ineffective against sub-micrometer viral particles. Thus, there's a critical demand for membrane filtration processes that combine robust filtration with antifouling and reaction -enabled functions for efficient pathogen disinfection. This research explores a novel microwave-assisted membrane filtration process incorporating catalytic reactions to enhance microbial disinfection and prevent membrane fouling, offering a groundbreaking solution to global challenges …

Lean Manufacturing Practices In Tanzania: Exploring Awareness, Training And Capital Investment, Francis D. Sinkamba

Tanzania Journal of Engineering and Technology (TJET)

With the growing competition among industries in the world, manufacturing industries are now forced to adopt the Lean Manufacturing philosophy to improve their competitive abilities. The adoption of the philosophy is very low in developing countries such as Tanzania, as is demonstrated with 1% of publications and the lack of knowledge and capital for Lean Manufacturing implementation causes this. Furthermore, the contribution of the sector to the Gross Domestic Product in Tanzania is low and stands at 8.4%. The study wants to bridge the gap in training, capital and awareness of Lean Manufacturing in Tanzania. Survey and purposive sampling techniques …

Modeling The Influence Of Internal Factors On Vehicular Mobility Performance, Aziz Mdimi

Tanzania Journal of Engineering and Technology (TJET)

Traffic mobility is significantly influenced by road conditions and the internal factors governing vehicular performance. Internal factors play a crucial role in vehicular mobility, influencing vehicles operate and performance. While existing vehicular mobility models primarily address external factors, external factors such as governor, engine, gear train and differential unit remain underexplored. This study formulates a comprehensive model to address this gap, focusing on the internal components that affect vehicular mobility. The proposed model employs both analytical and numerical methods to derive transfer functions for these subsystems using Matrix Laboratory (MATLAB), aiming to capture the dynamic behavior of vehicles under various …

Investigating The Impact Of Secondary Activation Time On The Adsorption Properties Of Activated Biochar For Arsenic Removal From Wastewater, Achyuth Bharadwaj Rayarao

Graduate Theses and Dissertations (2019 - present)

Biochar, a naturally occurring and renewable carbon material, becomes porous through activation. Activated biochar is an ideal candidate for use as an adsorbent. The objective of this study is to investigate whether activated biochar derived from Colorado soft pine serves as a better adsorbent and demonstrates enhanced adsorption capabilities after undergoing secondary physical activation at various activation times. The effect of secondary action time on physical adsorption properties drawn from the analysis of isotherm plots, surface areas and pore size patterns were examined by using a physisorption analyzer. Chemical structures were identified using both ultimate and proximate analyses, while porosity …

Micro-Mechanical Characterization Of Uhpc Stiffness Mechanisms: Towards A Better Understanding Of Concrete Elastic Modulus, Charissa N. Puttbach

Graduate Theses and Dissertations

Current design code equations for estimating the elastic modulus of specialty concretes like ultra-high performance concrete are not all suitable. Developing empirical curves from exhaustive experimental testing is challenging for concretes that may have high levels of cement replacement with mineral admixtures and fibers at varying volume contents. As such, an alternative approach is taken that seeks to understand the constituent microscale stiffness mechanisms and relate the results to the macroscale. Micropillars are fabricated on several cement paste phases using a focused ion beam. A modified pico-indenter is used to determine the linear and non-linear behavior under micro-compression loading. Micropillar …

General Hydrogeochemical Characterization Of Groundwater In Coastal Aquifers Of Kilwa Kisiwani Oceanic Island, South East Tanzania, Simon R Melchioly

Tanzania Journal of Engineering and Technology (TJET)

The main objective of this study was to determine the hydrogeochemical processes controlling the groundwater chemistry on the Island and assess its suitability for human consumption and irrigation. The methodology used in the study include hydrogeological assessment of the study area and laboratory analysis for general physico-chemical parameters of groundwater. Other parameters such as Soluble sodium percentage (SSP) or % Na+, Sodium Adsorption Ratio (SAR), Magnesium adsorption ratio (MAR), Residual sodium carbonate (RSC), hydrochemical facies classification, and Water Quality Index (WQI) were calculated using empirical formulae. The effects of salinization of groundwater were classified using the chloride-Bicarbonate (Cl/HCO3) and the …

Causes And Consequences Of Inefficient Drilling And Blasting In Mine Development Headings: A Case Study Of Hard Rock Gold Mining Operations In Northern Tanzania, George Bennett

Tanzania Journal of Engineering and Technology (TJET)

Despite the introduction of the perimeter blasting technique at the Tulawaka Gold Mine, the mine continued to suffer from an overbreak of mine development headings, with an average overbreak of 24% every 22 m, which is approximately twice the acceptable 10% overbreak. The causes of this problem include ineffective drilling practices and uneven and excessive charging of explosives, resulting in a slightly high powder factor of 3.94 kg/m3 instead of 3.8 kg/m3, as per the design. The problem of overbreak resulted in ore dilution, a longer mine development cycle time and additional costs of approximately US$ 45 per cut, especially …

Properties Of Portland Cement Concrete Incorporating Basalt-Based Pozzolanic Cement, Rana Khalil

Theses and Dissertations

Over the last decade, the world's population has increased dramatically. Due to this growth, the demand for concrete and Portland cement, in return, have increased. Manufacturing of Portland cement is an energy-intensive process that, alone, contributes to about 8% of global CO2. For decades, efforts have been exerted to reduce the harmful environmental impacts of Portland cement by reducing its use in concrete as well as considering alternate binders that may fully or partially replace it. This study aims to assess the properties of concrete incorporating a novel basalt-based pozzolanic cement. To meet this objective, four sets of concrete mixtures …

Mechanical And Electromagnetic Properties Of Incorporating Graphene Oxide In Cementitious Mixtures, Cherif Khalil

Theses and Dissertations

This multidisciplinary study aimed at investigating the impact of incorporating graphene oxide (GO) on the mechanical properties and electromagnetic (EM) shielding effectiveness of cementitious mixtures, as well as critically examining the mechanism with which GO affects their microstructure properties. Analysis of the literature review showed that there are discrepancies in reporting the impact of GO on the mortar mix. Consequently, this study focuses on exploring the cause for such discrepancies and identifies three main factors which are thoroughly investigated. The factors were the different sonication energies applied to the GO (Shear Mixing, 1.5 kJ/ml, 3 kJ/ml and 6 kJ/ml), the …

Tough Monolayer Silver Nanowire-Reinforced Double-Layer Graphene, Yanxiao Li, Congjie Wei, Steven E. Kooi, David Veysset, Chuanrui Guo, Yuxiang Gan, Ying Zhuo, Genda Chen, Mohammad Naraghi, Keith A. Nelson, Chenglin Wu

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Mixed-dimensional nanomaterials composed of one-dimensional (1D) and two-dimensional (2D) nanomaterials, such as graphene-silver nanowire (AgNW) composite sandwiched structures, are promising candidates as building blocks for multifunctional structures and materials. However, their mechanical behavior and failure mechanism have not yet been fully understood. In this work, we have performed integrated experimental, theoretical, and numerical studies to explore the performance and failure modes of graphene-AgNW composite under tensile and impact loading conditions. In situ tensile tests using a nano indenter, implemented with a push-to-pull device and a laser-induced projectile impact test system, are used to shed light on load-bearing mechanisms in graphene-AgNW …

Experimental And Finite Element Investigation Of Shear Transfer Mechanisms And Capacity Of Continuous Post-Tensioned Concrete Beams In One-Way Slab Buildings, Suman Rijal

Civil Engineering Theses - Archive

This study investigates the shear behavior and resistance mechanisms of continuous post-tensioned beams commonly used in one-way slab buildings. Combining experimental and analytical methods, the research focuses on the targeted failure regions of prestressed and non-prestressed continuous beams to gain deeper insights into their shear behavior. The large-scale specimens used in this study featured realistic parabolic tendon profiles and an average prestress level comparable to that used in actual construction. The experimental program includes three test series, with beam designs and setups refined for each series based on observations of shear crack development and progression in the preceding series. This …

Developing An Assessment Model For Entrepreneurship Ecosystems Using Hierarchical Decision Model, Mustafa Almuzel, Tugrul U. Daim, Birol Yesilada, Marina Dabic, Gulin Idil Bolatan

Engineering and Technology Management Faculty Publications and Presentations

Entrepreneurship is a crucial driver of economic growth, necessitating the development of effective entrepreneurial ecosystems. However, there are significant gaps in the literature regarding the structured assessment of these ecosystems. This study addresses three main research gaps: the lack of structured evaluation methods, the need for a comprehensive analysis of ecosystem challenges from various perspectives, and the identification of critical factors essential for ecosystem growth. To bridge these gaps, the research introduces the Hierarchical Decision Model (HDM) as a universal assessment framework that can be adapted to different cities for creating effective entrepreneurial environments. The research methodology involved formulating perspectives …

Impact Of Quenching Intensity Conditions On Using A Finite Element Model To Investigate The Microstructure And Hardenability Of Low-Alloy Steel, J. S. Alabi, E. Heidari, M. F. Buchely, K. Chandrashekhara, S. N. Lekakh, R. J. O'Malley, V. Athavale, A. Kumar

Materials Science and Engineering Faculty Research & Creative Works

Quenching is one of the primary processes to improve mechanical properties in steels, particularly hardness. Quenching is well established for different geometries of individually treated steel components; while in-steam quenching of large diameter continuously cast steel bar has several specific features which are difficult and costly to experimentally optimize. the end-quench Jominy test has been used extensively to study the hardenability of different steel grades. Different numerical, analytical, and empirical models have been developed to simulate the Jominy process and to understand quenching of steels. However, it is not straight forward to translate experimental data from Jominy test on instream …

Materials Of Lightweight Concrete Research, Meganne Chapman, Kathryn Burns, John Grubb

Williams Honors College, Honors Research Projects

The objectives for this research project are to explore options for innovative and sustainable materials in lightweight concrete. Various materials including granite powder, hydrated lime, latex, and recycled glass beads will be used in the concrete testing for this project. The question the team wants to answer is how these additives affect the concrete’s mechanical properties. Weekly mix designs will be performed, and control cylinders will be compared to experimental cylinders. Compression and tensile testing will also be performed to further aid the research. The motivation for performing this research is to aid mix development for the University of Akron …

Simulation Of Wave Propagation In Granular Particles Using A Discrete Element Model, Syed Tahmid Hussan

College of Graduate Studies: Theses & Dissertations

The understanding of Bender Element mechanism and utilization of Particle Flow Code (PFC) to simulate the seismic wave behavior is important to test the dynamic behavior of soil particles. Both discrete and finite element methods can be used to simulate wave behavior. However, Discrete Element Method (DEM) is mostly suitable, as the micro scaled soil particle cannot be fully considered as continuous specimen like a piece of rod or aluminum. Recently DEM has been widely used to study mechanical properties of soils at particle level considering the particles as balls. This study represents a comparative analysis of Voigt and Best …

Multi-Mode Regulation Of The Drying Process Of Industrial Gas, Isamidin Xakimovich Sidikov Pr, Nashvandova Gulruxsor Murot Qizi Phd

Technical science and innovation

Currently, much attention is paid to the issue of energy efficiency of gas processing enterprises. The continuous growth of world prices for energy resources requires constant improvement of the management system, providing the most optimal conditions for the flow of technological processes. A conceptual model of the heat-mass transfer process occurring in the absorber as an object of research has been developed, which characterizes the relationship of the variables involved in the drying process of natural gas, control, measurable and immeasurable, as well as controlled parameters have been selected, which are used to develop and study a mathematical model of …

Reducing Food Scarcity: The Benefits Of Urban Farming, S.A. Claudell, Emilio Mejia

Journal of Nonprofit Innovation

Urban farming can enhance the lives of communities and help reduce food scarcity. This paper presents a conceptual prototype of an efficient urban farming community that can be scaled for a single apartment building or an entire community across all global geoeconomics regions, including densely populated cities and rural, developing towns and communities. When deployed in coordination with smart crop choices, local farm support, and efficient transportation then the result isn’t just sustainability, but also increasing fresh produce accessibility, optimizing nutritional value, eliminating the use of ‘forever chemicals’, reducing transportation costs, and fostering global environmental benefits.

Imagine Doris, who is …

Modeling Of Asphalt Concrete For Cross-Anisotropic Visco-Elasticity And Heterogeneity, Zafrul Hakim Khan

Civil Engineering ETDs

Asphalt Concrete (AC) is a cross-anisotropic viscoelastic material. This study has developed a methodology to backcalculate the cross-anisotropic properties of the AC layer from the Falling Weight Deflectometer (FWD) sensor and pavement response data from embedded sensors inside a pavement section. This study has also developed a two-way coupled Multiscale Finite Element Model (MsFEM) with Phase Field Fracture (PFF) to study the microstructural heterogeneity and damage of the AC layer based on the actual field loadings. A Finite Difference Time Domain (FDTD) and Machine learning-based backcalculation algorithm were developed to determine the layer thickness and dielectric constant from air-coupled Ground …

Engineered Biomass-Derived Carbon Adsorbents For Targeted Contaminant Remediation From Aqueous Environments, Suraj Venkat Pochampally

UNLV Theses, Dissertations, Professional Papers, and Capstones

Porous carbon adsorbents like biochar (BC) are produced from waste biomasses like wood chips, animal litter, nut shells, dried grass, etc. to be used in a multitude of applications like gas capture, soil amendment, water treatment, electrode materials, etc. In water treatment, carbon-based adsorbents have been mainly used to physically or chemically adsorb contaminants depending on the adsorption mechanism. However, BCs in their raw state do not have the capability of absorbing high amounts of contaminants and need to be activated/ modified for the pore network to broaden and adsorb the contaminants with better efficiency.

The scope of this dissertation …

Structural Performance And Resiliency Of Reinforced Concrete Bridge Pier Columns, Multi-Column Piers, And Bridge Systems Subjected To Multiple Hazards – Fire, Collision, And Air Blast, Qusai Abdulkarim Alomari

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Given their close proximity to traffic and improper employment of protective systems, bridges and bridge piers are vulnerable to multi-hazard events triggered by vehicle collisions coupled with correlated and cascading events, such as explosions and fires. Despite recent catastrophic incidents that have highlighted the profound consequences of these extreme demands, including substantial damage, adverse economic impact, and loss of life, there has been a notable lack of research investigating the performance of bridges and bridge structural components under the aforementioned multi-hazards. Furthermore, current bridge design codes do not address these events assuming that, after these destructive events, replacement of the …

Initiation Criteria For The Onset Of Geomagnetic Substorms Based On Auroral Observations And Electrojet Current Signatures, Mayowa Michael Kayode-Adeoye

Graduate Theses and Dissertations (2019 - present)

In recent years, several substorm onset criteria have been developed, either from auroral observations (many authors) or from auroral electrojet properties such as those described by (Forsyth et al., 2015; Maimaiti et al., 2019; Newell & Gjerloev, 2011; Partamies et al., 2011) The different criteria are being investigated using a low order physics model of the magnetosphere called WINDMI (Spencer et al., 2009) and inferences are being made in line with the WINDMI model. The model variables will be compared with the criteria for substorm onset proposed by examining the SML index.

The WINDMI model uses solar wind and IMF …

Implementation Of Experimental Static Recrystallization Of High Strength Steel Into Computational Simulation Of Multi-Pass Slab Hot Rolling, S. K. Dasari, S. Ganguly, A. Abutunis, K. Chandrashekhara, M. F. Buchely, S. N. Lekakh, R. J. O'Malley, T. Natarajan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Microstructural changes and softening due to static recrystallization have a critical influence on thermo-mechanical behavior of high strength steels during industrial multi-pass hot rolling. Numerical simulation using finite element analysis (FEA) can be used to accurately predict the softening behavior during the hot rolling process. Therefore, the implementation of an experimentally defined static recrystallization model into FEA is necessary to get realistic simulation prediction. in this study, the extent of softening during static recrystallization in Si and Mn alloyed high strength steel was measured using double hit tests. a Gleeble™ thermo-mechanical simulator was used to perform the double hit tests …